On Oct 24, 2005, at 10:59 PM, Richard W. Harris wrote:
> I have been looking at the following for 80M: a) inverted-V, b)
> inverted-L, c) Delta loop for 80M. I can attach a 3-4 foot
> standoff on my tower at the top of any of the sections to attach
> any of these three antennas. My question is do you have any
> suggestions as to which of the three antennas (or any other you
> feel might be better) I might have the best luck with on this tower
> for 80M?
I had a similar situation yours, except I had an 80m shunt feed on my
15m tower, and needed something for 160m.
K9AY originally gave me this advice - run the shunt as high on the
tower as possible, then build a matching network to suit. He even
said he would help me with the matching networks - we could measure
the impedance of the shunt and compute a suitable matching network.
Then Gary moved away.
What I ended up doing was building a matching network for the shunt
for 160m. On 80m, I had found a workable omega match by trial with a
couple of big variable caps.
For 160m, it was clear I needed a wider matching range with an
inductive component. I created an L network using a coil wound around
a T200-2 toroid and a big cap. Using this I determined a Hi-Z network
would work. A few trials later, and I built a bigger toroid using two
stacked T200-2 cores and about 580-750 pf variable and fixed cap
combination. I made my first EU QSO on 160m just this week. It works.
You've already done the hard part -- laying down all the radials.
That 160m radial field will work great on 80m.
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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